1. Field of the Invention
The present invention relates to a totally-enclosed fan-cooled motor in which a stator in an air-tightly closed motor is cooled by means of an external fan provided out of the motor while a rotator is cooled by means of an internal fan provided in the motor.
2. Description of the Related Art
In a conventional totally-enclosed fan-cooled motor, an external fan provided on a side opposite to a drive side is used so that cooling air would flow in a first ventilation path formed in a stator to cool the stator while air is circulated in a second ventilation path formed in a core of a rotor and in a third ventilation path formed in a core of the stator in the air-tightly closed motor by means of an internal fan. This allows air in the motor to be heat-exchanged with air passing through the first ventilation path in a process of flowing in the third ventilation path, and thereby, to be cooled (refer to JP-A-2003-143809, for example).
In such a conventional totally-enclosed fan-cooled motor, the external fan can function as a coolant, and thereby, cool the heat in a bearing provided on a side of the external fan. A bearing provided on a drive side opposite to the side of the external fan, however, is difficult to be cooled, so that there is a problem that deterioration in bearing grease is likely to occur.